Research On The Influence Of Large Diameter Curve Pipe Jacking On Adjacent Pile Foundation And Optimization Of Wall Thickness

The development and utilization of underground space is the theme of the 21 st century.With the continuous promotion of urbanization and the rapid growth of urban population,the scarcity of land resources has become increasingly apparent,and the development and utilization of underground space has become an important way to solve the problems of big cities.At present,the underground project is mainly dominated by the underground rail transit,while the municipal foundation implementation,represented by the underground comprehensive pipe gallery,gradually rises and reaches the construction climax.In municipal drainage construction,shield construction and pipe jacking construction are two main underground excavation methods.The similarity is that both of them do not need to excavate the earth surface to reduce the impact on the existing traffic and environment of the city.During the excavation,both of them use the heading cutter to cut the soil and complete the subsequent jacking.The difference is that after the shield method completes,the cutting of the previous ring segment uses the previously installed segment to provide support and complete the subsequent nose jacking.However,the pipe jacking method mainly relies on the jack to push the pipe section forward,and the rest pipe sections are put into the working hole to complete the overall advance of the pipe section.On this basis,this article relies on Haikou meilan airport phase ii off-site drainage project,analysis the influence degree of pipe jacking on bridge pile foundation,the subsidence deformation of surface,the change rule of stress state of pipe and the stress and deformation rule of the bothsides of the curve pipe jacking,which has guiding significance to actual project.First,ABAQUS finite element software was used to establish a three-dimensional finite element model based on the field data of the project.According to the existing construction conditions,the construction process of big diameter curve pipe jacking was simulated.The three-dimensional finite element model is established by using key technologies such as element life and death,element replacement and field variables,taking the interaction of soil excavation,addition of segments and grouting layers,stress release of excavated soil and strength change of grouting layers,as well as the interaction of complex stress fields such as grouting pressure,jacking force,friction resistance and ground stress into consideration.The stress variation of the pipe jacking during the construction period,the stress displacement distribution on bothsides of the pipe jacking curve and the influence on the stress displacement of adjacent bridge pile foundation and soil were analyzed.Secondly,pipe wall thickness optimization was carried out based on the original model,and the influence of pipe wall thickness on the stress deformation,the surrounding bridge pile foundation was comprehensively considered,so as to obtain the optimum thickness of pipe wall and guide the construction.Finally,based on the finite element software ABAQUS,this paper analysis the modal and seismic dynamic response of the tube-soil structure,and studies the response laws of acceleration,displacement and stress of the tube-jacking structure under the most adverse conditions in all directions of earthquake action.The results can be used as a reference for seismic design of similar projects.